Liquid crystal displays (hereinafter, also referred to as “LCDs”) have become widespread as lightweight, thin displays that achieve low-power consumption. In recent years, improvement in display quality and an increase in size have resulted in increased demand for large-sized liquid crystal television sets. LCDs are essential for daily life and business. For example, a liquid crystal display method is often employed for mobile use and various monitors. In the technical field of such LCDs, in order to enhance competitiveness in the market, there have been advances in the development of LCDs to improve display quality, such as an increase in viewing angle and improvement in contrast, and to impart a lot of functions.
In LCDs that have been developed so far, various display modes are used. The display modes are categorized by the arrangement state of liquid crystal molecules when no voltage is applied and the direction of an applied electric field. In particular, a liquid crystal display element in a longitudinal electric field mode in which the alignment of a liquid crystal is perpendicular to a substrate when no voltage is applied is referred to as a vertical alignment-mode element or a VA-mode element. This mode is advantageous to achieve a wide viewing angle and high contrast. Thus, the use of the mode is being expanded.
The basic structure and the operation principle of LCDs are as follows: A liquid crystal layer (liquid crystal medium) is held between substrates. The application of a voltage to electrodes arranged on the substrates changes an electric field state in the liquid crystal layer to control the alignment of liquid crystal molecules and to change the polarization state of light transmitted through the liquid crystal layer, thereby adjusting the quantity of light transmitted through a polarizing plate to change gradation levels. Thereby, an image is displayed. In the VA mode, the alignment state of liquid crystal molecules is controlled by the use of a nematic liquid crystal composition having a negative dielectric constant anisotropy. The display performance of LCDs is significantly affected by the display mode. The liquid crystal composition constituting the liquid crystal layer also greatly affects the display quality and performance.
With respect to the nematic liquid crystal composition having a negative dielectric constant anisotropy applicable to the VA mode and so forth, various liquid crystal molecules, compositions containing the liquid crystal molecules, and liquid crystal display elements are disclosed, the liquid crystal molecules containing compounds having trifluoronaphthalene skeletons and difluorochroman skeletons, derivatives thereof, and polycyclic compounds as additional components (for example, see PTLs 1 to 4). These literatures state that these liquid crystal compositions have high degrees of negative dielectric constant anisotropy and are capable of improving the display performance of the liquid crystal display elements. In addition, liquid crystal compositions and so forth containing compound groups having various difluorochroman skeletons and additional components (for example, see PTL 5) and compound groups and so forth having various trifluoronaphthalene skeletons (for example, see PTL 6) are disclosed.
Furthermore, a liquid crystal composition is disclosed which contains a compound group, serving as a first component, in which one or two alicyclic structures are bonded to a trifluoronaphthalene skeleton with an ether linkage, a compound group, serving as a second component, in which one or two alicyclic structures are bonded to a difluorochroman skeleton with an ether linkage, and so forth (for example, see PTL 7).